The invention relates to a method and an apparatus, which is used to exchange an application roller for applying glue to the spine of a book block transported in a conveying direction by rolling off the book block spine, and which is aligned with a duct roller that removes glue from a glue container. For this, a first application roller that makes contact with the duct roller is swiveled away from the duct roller, is then exchanged for a second application roller, and this second application roller is subsequently swiveled back against the duct roller, wherein the first and the second glue application rollers have a joint drive shaft and wherein the duct roller and the joint drive shaft for the application rollers respectively have a separate axis of rotation which is arranged substantially normal to the book block conveying direction. The invention furthermore relates to a book production line equipped with such a apparatus.
During a book production operation, the book blocks which still lack a book cover are conveyed with a transporting device while an application roller that operates jointly with a duct roller respectively rolls off the book block spine and, in the process, applies the glue. In a following operational step, the glue applied to the book block spine serves to join the book block to the book cover. Since the spine contour can be straight or rounded, a correspondingly embodied application roller is used in each case. Known application rollers, for example, are therefore embodied either flat or profiled.
These or similar methods and devices are disclosed in European Patent documents EP0873882 A1, the DE3502733 C1 and DE4332069 A1.
In most cases, a new book production order results in a change of format for the books to be produced. Owing to the fact that the application roller for applying glue to the book block spine is respectively designed for a specific book block format, the roller must be exchanged for an application roller that corresponds to the new format in the case of a format change.
In the case of a new book production order for which the format deviates from the previously used book format, the production line must initially be stopped for safety-technical reasons since the exchange, meaning the removal and/or installation of an application roller, can be realized only while the casing is open. The machine is therefore stopped following the application of glue to the spine of the last book block in the previous production order. Once the casing is opened, the previously used application roller is dismantled and a suitable application roller for the new production order is installed. With the known methods, the application roller is always replaced manually.
According to a first known method, the application roller is initially swiveled away from the duct roller with the aid of a manually operated adjustment spindle and is then removed manually, meaning it is axially pushed down from the drive shaft and then transported away. A new application roller is subsequently pushed in the axial direction onto the drive shaft, is locked in place thereon, and is then moved with the manually operated adjustment spindle against the duct roller. Following the closing of the casing, the production can be restarted and the new production order processed.
According to a second known method, the contact between the application roller and the duct roller is manually interrupted for the exchange operation, using an eccentrically positioned drive shaft, and the new application roller is then moved against the duct roller. Once the eccentric positioning is secured and the casing is closed once more, production can resume and the new production order can be processed.
With the known methods and the known devices for exchanging an application roller, the application roller is moved manually away from and/or against the duct roller. In the process, the application roller to be exchanged, which is located inside the machine, is initially moved far enough away from the duct roller so that during the subsequent operation of pulling the application roller from the drive shaft in the axial direction, its largest outside diameter does not come in contact with the duct roller. The same also applies for the new application roller to be installed in the machine by pushing it in the axial direction onto the drive shaft. Once the new application roller has been moved into place, contact needs to be re-established between the application roller surface and the duct roller, meaning the distance between the rotation axis of the new application roller and the rotation axis of the duct roller and, in particular, the contact pressure between the two rollers must be adjusted correctly. On the one hand it means that the contact pressure needs to be high enough to ensure that glue is transferred from the surface of the duct roller to the surface of the application roller. On the other hand, the contact pressure should not be too high since that would result in unnecessary wear for the application roller. Owing to the fact that moving the application roller away from and/or against the duct roller is manually controlled and the actual spacing and the contact pressure consequently depend on the feeling of the machine operator, a precise reproducibility of the process is not possible and an increase in the wear of the application roller cannot be precluded. In addition, the manual control of the complete exchange operation is relatively time-consuming and the share of time that is required for the changeover is relatively high, especially for smaller production runs.